1. Field of the Invention
The present invention relates to an illumination arrangement which comprises an illumination means and a light permeable base body having light permeable profiled bodies formed by recesses in the base body to direct light from the illumination means to a light emission surface of the base body. In particular an illumination arrangement which can be used in light fittings, display screens etc. .
2. Description of the Related Art
Illumination arrangements of the kind set out above are for example also employed as covers or screens for light fittings. Thereby it is already known to use screens having profiled bodies formed and projecting on the side towards a lamp of the lamp fitting, for directing the light of the lamp of the light fitting, in order to restrict the emission direction of the light rays, for reducing dazzling of an observer. In GB-A-1365507 it is proposed for this purpose to form the profiled bodies in the shape of truncated pyramids, which project from the base body of the screen, the upper bounding surfaces of the truncated pyramids being coated with a light impermeable material. In U.S. Pat. No. 3,351,753 there is likewise proposed a screen having profiled bodies in the shape of truncated pyramids, whereby however in this case the side surfaces of the truncated pyramids and the intermediate spaces between the truncated pyramids are coated with a light impermeable material.
By means of these known screens there is achieved a directing of light suitable for restricting the angle of emission of the light rays, but due to the non-transparent regions of the screen the efficiency of the light fitting is reduced. In AT-A-301/87 there was therefore proposed a screen for light fittings likewise having pyramid-like profiled bodies, which are arranged in a matrix form on the side of the base body of the screen towards the lamp of the light fitting and having an upper bounding surface running parallel to the emission surface of the screen, the entire screen being of a transparent material.
The individual glass profiled bodies of this screen known from AT-A-301/87 are so configured that light emitted from the lamp of the light fitting onto the upper bounding surface of the individual profiled bodies is carried by the profiled bodies to the emission surface of the screen and emitted there within a predetermined maximum emission angle range. However, since this form of screen is preferably employed together with elongate fluorescent lamps, problems appear in the coupling of the light emitted from the lamp employed into the glass profiled body, since the lamp naturally irradiates not only the upper bounding surfaces of the individual profiled bodies but also the (light permeable) side faces of the truncated-pyramid-like profiled bodies. This, however, has the result that the desired maximum emission angle for avoiding dazzling of the observer cannot be maintained without further measures, since the light emitted from the lamp is not only directed towards the emission surface of the screen in the interior of the individual profiled bodies, but is also reflected or refracted at the side surfaces of the profiled bodies.
Further, there is known from EP 0 345 468 A2 an illumination arrangement as an broad area irradiator with which a plurality of luminescence semiconductor bodies, as luminous means, are applied to a light permeable base body in a extensive distribution. However, the base plate of this illumination arrangement has no profiled bodies for directing light, such as are for example known from the above-mentioned AT-A-301/87.
Moreover, there is disclosed in U.S. Pat. No. 5,272,410 an illumination arrangement which comprises an illumination means and a light permeable base body having light permeable profiled bodies formed by recesses in the base body to direct light from the illumination means to a light emission surface of the base body. The illumination arrangement is in this case a light emitting body, which can be used for example as tail light for motor vehicles. It consists of two plates of which at least one has a series of prismatic recesses the walls of which are coated with a phosphorescent layer. The recesses contain a gas under partial vacuum. At the ends of the glass plates electrodes are arranged by means of which, through gas discharge in the recesses, light is generated at the phosphorescent layer, which light is emitted in various directions. The outside of one of the two glass plates is provided with a reflecting layer, so that this reflector and the prismatic structure of the recesses provide that the light is so directed that it is emitted at the side of the body away from the reflector. With this illumination arrangement, however, the light is not emitted at a restricted angle of emission for reducing dazzling of an observer.
The present invention thus has the object of providing an illumination arrangement having profiled bodies formed in a base body with which on the one hand the above-described light coupling into the individual profiled bodies is facilitated and on the other hand a higher optical efficiency, preferably with sufficient anti-dazzling effect, is realized.
In accordance with the present invention this object is achieved by means of an illumination arrangement of the type described above in regard to U.S. Pat. No. 5,272,410, wherein the luminous means are applied to upper bounding surfaces of the profiled bodies and emit light into corresponding profiled bodies through upper bounding surfaces thereof. In other aspects, the invention also includes further features, as will be seen from the specification. The subclaims describe preferred embodiments of the present invention, which for their part contribute to a manufacturability of the illumination arrangement in accordance with the invention which is as efficient as possible and allows series production, or contribute to a best possible optical efficiency with best possible anti-dazzling effect.
In accordance with the present invention there is applied directly on the profiled bodies of the illumination arrangement in accordance with the invention (in particular on the upper bounding surfaces of the profiled bodies), a luminous means which emits light into the corresponding profiled body. The profiled bodies are of a light permeable material and, in their interior, direct the light emitted from the luminous means towards the emission surface of the illumination arrangement, where the light of the luminous means is emitted. Thereby, the individual profiled bodies are preferably so configured that the illumination arrangement at each arbitrary point of its emission surface emits the light of the luminous means within a predetermined maximum emission angle range of for example 60xc2x0 to 70xc2x0 in order to avoid a dazzling of an observer due to too flatly emitted light.
The individual profiled bodies may be formed for example in the manner of truncated pyramids, or elongate in the form of strips. As luminous means there may be considered for example a diffusely illuminating layer of organic or inorganic semiconductor materials, whereby electroluminescence is excited in these semiconductor materials by means of the application of electric voltage.
The profiled bodies of the illumination arrangement in accordance with the invention are separated from one another by means of recesses formed in the base body of the screen, whereby these recesses may in particular be V-shaped. The flanks of these recesses or the side flanks of the profiled bodies may be straight or curved. Advantageously, the side flanks of the profiled bodies are so formed as to be reflecting at their inner faces, so that the light is completely reflected within the profiled bodies. The same effect can be achieved by means of a configuration of the individual profiled bodies in such a way that in dependence upon the refractive index of the profiled bodies the light falls onto the inner faces of the side flanks of the profiled bodies exclusively at an angle of total reflection.
In accordance with a preferred exemplary embodiment, the individual profiled bodies are formed in a foil which is attached to a carrier of a light fitting, in particular glued thereto.
The advantage of the present invention consists in that the luminous means applied to the profiled bodies provide the light source for the corresponding illumination arrangement. If the luminous means are provided in the form of illuminating layers, a very flat illumination arrangement can correspondingly be realized. Since the luminous means are applied directly to the profiled bodies, with the illumination arrangement in accordance with the invention the above-described problem of light coupling does not appear in practice. Since a light fitting with the illumination arrangement in accordance with the invention does not need a lamp or lamp mounting, no lamp changing is needed. Such a light fitting has, depending upon the luminous means employed in each case, a long lifetime.
The lighting arrangement in accordance with the invention can be employed in particular in combination with one or more flat fluorescent lamps, which serve as luminous means and bear directly on the upper bounding surfaces of the profiled bodies. In this manner the above-described advantages of the present invention can be combined with the advantages of such fluorescent lamps, such as e.g. a flat configuration and a constant, high light density.